In developing economies, the "middle class" is usually take to run from $2/day to $20/day in consumption per person. By that standard, here's what Africa's distribution of income looked like in 2010:

The African Development Bank reports: "Recent estimates put the size of the middle class in the region in the neighborhood of 300 to 500 million people, representing the population that is between Africa's vast poor and the continent's few elite. Africa’s emerging middle class comprises roughly the size of the middle class in India or China."

The increase in the middle class has been substantial in the last few decades. The middle class was 26.2% of the population in 1980, 27% in 1990, 27.2% in 2000--and then 34.3% in 2010. To be sure, a lot of this growth was in the lowest level of the middle class, those consuming $2-$4/day on a per person basis. If one looks only at the middle class from $4-$20/day, their share of the population actually declines a bit from 1980 to 2010. The progress here is obviously slow, but nonetheless seems real.

The middle class is important for a number of reasons. It creates a local market that didn't exist before for many goods and services, and can have a positive effect on governance. The ADB reports:

"Strong economic growth in the past two decades has helped reduce poverty in Africa and increased the size of the middle class. Although the growth in Africa’s middle class has not been very robust, it has nonetheless been noticeable and contributed to increased domestic consumption in many African countries, a development that could help to foster private sector growth in African countries. Sales of refrigerators, television sets, mobile phones, motors and automobiles have surged in virtually every country in recent years. Possession of cars and motor cycles in Ghana, for example, has increased by 81% since 2006. As such, the middle class is helping to foster private sector growth in Africa as they offer a key source of effective demand for goods and services supplied by private sector entities.

The middle class is also helping to improve accountability in public services through more vocal demands for better services. The middle class is better educated, better informed and has greater awareness of human rights. It is the main source of the leadership and activism that create and operate many of the nongovernmental organizations that push for greater accountability and better governance in public affairs, a position that augurs well for creating a suitable environment for growth and development."

And here's one other statistic that jumped out at me: "The number of internet users [in Africa], which can be used as a proxy for middle class lifestyles, has increased from about 4.5 million people in 2000 to 80.6 million people in 2008."